1. Field of the Invention
The present invention relates to a jet-propulsion personal watercraft (PWC) which ejects water rearward and planes on a water surface as the resulting reaction. More particularly, the present invention relates to a personal watercraft comprising an engine cooling system adapted to discharge cooling water in an engine to outside of the engine after use.
2. Description of the Related Art
In recent years, so-called jet-propulsion personal watercraft have been widely used in leisure, sport, rescue activities, and the like. The jet-propulsion personal watercraft is configured to have a water jet pump that pressurizes and accelerates water sucked from a water intake generally provided on a bottom of a hull and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.
In the jet-propulsion personal watercraft, a steering nozzle provided behind the outlet port of the water jet pump is swung either to the right or to the left, to change the ejection direction of the water to the right or to the left, thereby turning the watercraft to the right or to the left.
In the jet-propulsion personal watercraft, a base end of a supply passage of the cooling water is connected to a pressurizing portion of the water jet pump and a tip end of the supply passage is connected to a cooling water supply port of the engine so that part of the water pressurized by the water jet pump is branched and supplied to a cooling water supply passage of the engine. In such a constitution, since the water intake is provided on the bottom of the watercraft, sand, waterborne plants, dust, substances, or the like are sometimes sucked into the water jet pump and the cooling water supply passage of the engine which is connected to the pump, through the water intake.
It is preferred that the cooling water in the engine be discharged outside after use for prevention of corrosion of the inside of a water jacket of the engine. In some cases, however, the cooling water in the engine is difficult to discharge outside, depending on the constitution of the cooling water supply passage.
The present invention addresses the above described condition, and an object of the present invention is to provide a personal watercraft that offers easy inspection and maintenance and is capable of preventing substances mixed in cooling water from going into an engine side, and also easily allows discharge of the cooling water from the engine after use.
According to the present invention, there is provided a personal watercraft comprising: a water jet pump including an outlet port, the water jet pump pressurizing and accelerating sucked water and ejecting the water from the outlet port to propel the watercraft as a reaction of the ejecting water; a riding seat; a water-cooled engine placed in an engine room below the seat, for driving the water jet pump; a supply passage through which cooling water is supplied from outside of the watercraft to the engine; and a filter provided in the supply passage for filtering substances in the cooling water.
In the personal watercraft so constituted, since the substances in the cooling water such as sand can be eliminated by the filter provided in the supply passage of the cooling water, entry of the substances into the engine can be prevented.
It is preferable that, in the personal watercraft, a tip end of the supply passage is connected to a cooling water supply port of the engine and the supply passage extending from a connecting portion to the cooling water supply port toward a base end of the supply passage is positioned so as to be as high as or lower than the cooling water supply port. In the personal watercraft so constituted, after cruising, the cooling water in the engine is discharged by its gravity toward the supply passage. Since there is no cooling water in the engine after use, the corrosion in the water jacket of the engine, which would be caused by the cooling water that resides in the engine, can be prevented.
It is preferable that the personal watercraft further comprises an opening provided in a body of the watercraft under the seat, the riding seat is removably provided so as to cover the opening in the body of the watercraft and the filter is placed so as to be visible through the opening when the riding seat is removed. In this constitution, the filter requiring inspection and cleaning, can be easily inspected and cleaned by removing the riding seat.
It is preferable that, in the personal watercraft, the filter is provided on a pump casing placed behind the engine. This constitution enables the filter to be easily inspected and cleaned.
It is preferable that, in the personal watercraft, the supply passage has a protruded portion curved so as to be partially protruded upwardly toward the opening in the body and the filter is provided on a top portion of the protruded portion. This constitution enables the filter to be easily inspected and cleaned.
It is preferable that, in the personal watercraft, a tip end of the supply passage is connected to a first cooling water supply port of the engine and a bypass passage that bypasses at least the protruded portion is provided so as to be as high as or lower than the first cooling water supply port. The cooling water in the engine is discharged by its gravity to the outside of the watercraft through the bypass passage. As a result, since there is no cooling water left in the engine after use, the corrosion in the water jacket of the engine, which would be caused by the cooling water that resides in the engine, can be prevented.
It is preferable that, in the personal watercraft, the bypass passage has a flow cross-sectional area smaller than a flow cross-sectional area of the supply passage. Thereby, without occluding the bypass passage during engine operation, substances such as sand in the cooling water supplied from outside the watercraft to the engine can be suppressed with a simple constitution.
It is preferable that, in the personal watercraft, a one-way valve is provided in the bypass passage to permit only a flow from an engine side. This constitution is capable of preventing the substances from going into the engine through the bypass passage.
It is preferable that, in the personal watercraft, both ends of the bypass passage are connected to the supply passage, and a flow passage extending from a connecting portion to the first cooling water supply port toward a base end of the supply passage through the bypass passage is positioned so as to be as high as or lower than the first cooling water supply port.
It is preferable that, in the personal watercraft, one end of the bypass passage is connected to the supply passage between the protruded portion of the supply passage and the tip end of the supply passage and the other end thereof communicates with outside of the watercraft, and a flow passage extending from the first cooling water supply port to the outside of the watercraft through the supply passage and the bypass passage is positioned so as to be as high as or lower than the first cooling water supply port.
It is preferable that the personal watercraft further comprises a second cooling water supply port of the engine, and one end of the bypass passage is connected to the second cooling water supply port and the other end thereof is connected to the supply passage between the protruded portion and a base end of the supply passage, and a flow passage extending from the second cooling water supply port to the outside of the watercraft through the bypass passage and the supply passage is positioned so as to be as high as or lower than the second cooling water supply port.
It is preferable that the personal watercraft further comprises a second cooling water supply port of the engine, and the bypass passage is provided between the second cooling water supply port and the outside of the watercraft so as to be as high as or lower than the second cooling water supply port.
It is preferable that, in the personal watercraft, at least a part of a casing of the filter is comprised of a member through which filtering residue remaining in the filter is visible. Thereby, whether or not the filter should be cleaned can be easily checked from outside.
It is preferable that, in the personal watercraft, the filter is removably mounted, because the filter can be easily removed and cleaned.
It is preferable that, in the personal watercraft, the water jet pump is used as a cooling water supply pump for supplying the cooling water to the supply passage. This constitution is rational because there is no need for an additional cooling water supply pump. Further, after cruising, the cooling water in the engine can be easily discharged through the water jet pump as the cooling water supply pump.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.